In case any one is interested, I wrote up a short note on why one should
not specify unanalyzed elements, in Excel or other apps which do not
calculate the change in the matrix physics. Particularly if these
unanalyzed elements are present at major element weight percent levels:
https://probesoftware.com/smf/index.php?topic=92.msg7697#msg7697
This matrix effect of unanalyzed elements can be significant even in
cases where the unanalyzed elements are only a few percent of the total,
for example water by difference calculations in alkali glasses.
It does depend somewhat on the specific emitters and compositions
involved, but the magnitude of the effect on the analyzed elements
surprised me when I first noticed it. In the case of water by
difference, it turns out that Si Ka is more heavily absorbed by water
(oxygen) than by Si, so adding water to the matrix correction increases
the Si concentration, which in turn decreases the water by difference
calculation. Which is why the water by difference calculation needs to
be in the matrix correction iteration loop.
john
On 10/12/2018 9:53 AM, John Donovan wrote:
>
> All,
>
> I know nothing about the JEOL software and haven't looked at Julien's
> script, but technically one should include the calculated CO2 in the
> matrix correction, because adding these unanalyzed elements does
> change the matrix correction physics, often significantly.
>
> I think I'll write up a short post on this issue on the Probe Software
> User Forum.
>
> john
>
>
> On 10/12/2018 4:11 AM, Allaz Julien wrote:
>> Hi Tod,
>>
>> I personally do not use the JEOL software for calculating the CO2
>> content. During the analysis, I simply specify a fixed amount (44%
>> for calcite, 52% for magnesite, 38% for Fe-rich one, or an
>> intermediate value), and recalculate the CO2 content offline using my
>> little web-based script or an XL spreadsheet.
>>
>> My own online tool is available here, you can simply copy & paste
>> data from excel (without the column “total”):
>> http://ethz.geoloweb.ch/index.php?page=mineral_formula&reset=true
>>
>> Cheers,
>>
>> Julien
>>
>>
>>> On 12 Oct 2018, at 13:01, Tod Earle Waight <[log in to unmask]
>>> <mailto:[log in to unmask]>> wrote:
>>>
>>> Hi all
>>> I am running carbonates and having issues wrapping my head around
>>> the JEOL software.
>>> I have set up the analyses as oxides, with CO2 added. In the element
>>> condition option under CAL I have the option to define how many CO2
>>> are added for a group of specified elements and I have set up so (as
>>> I understand things) it should add 1 CO2 for 1 Ca, 1 Mg and 1 Fe.
>>> However, the software only adds CO2 for the first element on the
>>> list – So I can run a calcite and it works perfectly, but if I run
>>> a dolomite it adds CO2 for Ca but not Mg.
>>> Is this a software is or am I just doing something dumb!
>>> Cheers
>>> Tod
>>> PS I am running a JEOL8200, with software from 2011 (VO1.55)
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>
> --
> John J. [log in to unmask]
> University of Oregon (541) 346-4632 (office)
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--
John J. Donovan [log in to unmask]
University of Oregon (541) 346-4632 (office)
1443 E. 13th Ave (541) 346-4655 (probe)
Eugene, OR (541) 346-6854 (FAX)
97403-1241
CAMCOR Web: http://camcor.uoregon.edu/
Facility Web: http://epmalab.uoregon.edu/
Cameca SX100 Schedule: http://camcor.uoregon.edu/wp/calendar/sx100
FEI Quanta Schedule: http://camcor.uoregon.edu/wp/calendar/sem
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Electron Microprobe Lab, University of Minnesota
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